Process for making lubricating oils



Jan. 14, 1941. RJF. BEfiSTR' M 2,228,500-

PROCESS FOR MAKING LUBRICATING OILS Filed April 27, 1940 Patented Jan.l4, 1941 UNITED STATE PROCESS FOR MAKING LUBRIOATING OILS Roland F.Bergstrom, Oakland, Calif., assignor to Shell Development Company,

San Francisco,

Calif., a corporation of Delaware Application April 27, 1940, Serial No.331,988

9 Claims.

This invention deals with a method for incorporating metal bases intolubricating oils containing organic acids.

It is known that the presence of certain metal salts of organic acids inlubricating oils have certain beneficial efiects, in that these metalsalts improve various properties of the oil such as corrosionprotection, ringsticking prevention, ex-

treme pressure properties, oiliness properties, 10 wear prevention,resistance to oxidation, etc.

It is a purpose of this invention to provide a simple method wherebymetal bases can be introduced into lubricating oils containing organicacid components. It is a further purpose to produce lubricating oilscontaining metal salts of organic acids, which salts are difficult toproduce or diificult to dissolve or both; and it is a further purpose toutilize organic acids already contained in mineral oils to serve as theacid component of 20 the salts which the finished oil shall contain.

I have discovered that oils containing varying amounts of organic acidscan be made to'react with metal oxides or hydroxides if theacid-containing oil is heated with a suitable amount of 5 the metal baseto an elevated temperature and under a superatmospheric pressure in thepresence of a small amount of aqueous ammonia. The reaction proceedsreadily if the salt produced thereby is oil-soluble. Hence, a metal baseshould 30 be selected which produces an oil-soluble salt with the acidcontained in the oil. It is in general preferred to carry out thereaction with a stoichiometric amount or a slight excess there-- over,of the metal base required to neutralize the 35 acid contained in theoil, or, if desired, to produce the basic salt'if a polyvalent metalbase is employed.

Organic acids which may be conveniently converted to their saltsolutions by my process are,

40 for example, phenols, alky'l phenols, thiophenols, alkyl' naphthols,naphthenic acids, fatty acids, aromatic fatty acids, aromatic carboxylicacids in which the carboxyl radical is directly attached to the aromaticnucleus, rosin acids, paraflin' 45 acids produced by oxidation ofparaflins, wool fat acids, chlorinated or hydroxy derivatives of theabove acids, oil-soluble sulfonic acids, such as mahogany sulfonicacids, etc.

50 Practically all metalbases which form oilsoluble salts with the aboveacids may be used in the process. Thus the alkali metal hydroxides,

alkali earth oxides or hydroxides, particularly magnesium or calciumoxides or hydroxides; the 55 oxides or hydroxides of Cu, Zn, Cd, Al, As,Sb, Bi,

Cr, Mo, W, Mn,:Fe, Co, and Ni may be introduced successfully.

Many of the salts of the above acids and bases are very diflicult toproduce, by other methods, and some salts, even if obtainable, tend tode- 5 compose when it is attempted to dissolve them in lubricating oils,or they refuse to go into solution. For example, calcium or aluminumcresylates are almost impossible to dissolve in lubricating oil by meansother. than those herein de- 1 scribed, whereas by my method, nodifficulty is experiencedin obtaining fairly concentrated solutionsofthese cresylates. 1

A particular advantage of my method resides in the fact that basic saltscan easily be produced, which salts are often difllcult to obtain,particularly when weak acids or weak bases or both are involved.

The amount of aqueous ammonia required may vary over a considerablerange. In general, from about .l% to 5% by volume of concentrated (28%to 30%) aqueous ammonia may be added to the oil, or an equivalent amountof more dilute ammonia. In general, however, it is proposed to useammonia of at least about 10% concentration.

The temperature of reaction may vary from about 300 Ffiup to theincipient cracking temperature of the oil and is preferablyv betweenabout 500 to 700 F. The time of reaction generally required may varyfrom about .01 to 10 seconds, depending upon the temperature used,although a longer timemay be allowed at temperatures low enough toprevent undesirable side reactions. The superatmospheric pressuresmaintained may range advantageously from about 15 to 500 pounds persquare inch (gauge), but preferably 50 to 200 pounds per square inch(gauge) After having contacted the mixture of oil .containing theorganic acid, metal oxide base and aqueous ammonia at .the desiredelevated tem- 40 perature and pressure, the pressure is released,whereupon water and ammonia'escape, and the reacted oil is then cooledat the reduced pressure, which is most conveniently atmosphericpressure.

Usually the resulting oil is somewhat cloudy, I

containing unreacted'metal base, which can be removed by simplefiltration or centrifuging.

Depending upon the solubility of the salt produced by the reaction,various amounts of salts can be incorporated by my method. Saturatedsolutions, and occasionally even supersaturated solutions, may beproduced;

My process will be more fully understood from the accompanyingdrawingwhich represents one form of an apparatus which may be usedconveniently in producing my compounded oils. Lubricating oil containingan amount of an organic acid metal base and aqueous ammonia is pumpedfrom storage tank I by pump 2 in line 3 into reaction tube 4 situated infurnace I. Pressure on the reaction tube is maintained by'valve 8 inrundown line I.

Tank I is equipped with a stirrer 8 and hopper 9, the latter being usedto introduce the metal base. Aqueous ammonia is introduced into tank Ithrough line I0. During operation, stirrer 8 @eps a uniform suspensionof the metal oxide and ammonia in the oil.

R'eacted oil flows through rundown line I to separator II equipped withvent line I2. Hot oil from the separator passes through cooling coil I3into storage tank I4.

It is of interest to note that the process should be operated by thecontinuous method described in the drawing, rather than by the batchmethod. It has been found that batch operation is accompanied bydifliculties, possibly because of the impossibility of. properlycontrolling the various factors of time element, quick pressure releaseto remove water and ammonia just at the proper moment, etc. Thus, whilethe presence of water may be a cause for difficulty under somecircumstances, it has been observed that,'on the other hand, itspresence, together with that of ammonia, is essential for the promotionof the reaction.

The following examples further illustrate my invention Example I Alubricating oil containing 20% of an alkyl phenol mixture was mixed with7% by weight calcium hydroxide. 5% by weight of 28% aqueous ammonia wasadded. The resulting mixture was strongly agitated to maintain a uniformsuspension, which was fed at a rate of about 3 to 4 gallons per hourthrough an externally heated ,ance to oxidation and fairanti-ringsticking properties.

Example II A mineral oil containing 20% naphthenic acid was treated with7% by weight magnesium hydroxide under the conditions of Example I. An

oil was produced containing 22% basic magnesium naphthenate. This 011was filtered and blended with straight lubricating oil to produce ablend having a content of basic magnesium naphthenates of 1.2%.Thisblend proved to be a lubricating oil having excellentanti-ringsticking properties.

I claim as my invention:

1. Process for incorporating a metal base in a lubricating 011containing an amount of an organic acid, said metal base and organicacid beingcapable of forming an oil-soluble salt, comprising mixing said011 with said metal base and a small amount of strong aqueous ammonia,heating: the mixture to a temperature between 300 F. and incipientcracking temperature of said oil at a superatmospheric pressure for aperiod of about .01'to 10 seconds, releasing the pressure whereby waterand ammonia are allowed to escape, and cooling the resulting oil.

2. Process of claim 1 wherein the aqueous ammonia has a concentration ofabout 10% to 30%.

3. Process of claim 1 wherein the amount of aqueous ammonia isequivalent to between .1%

-to 5% of concentrated ammonia by volume ofamount being at leastequivalent to said acid,

and a quantity of a strong aqueous ammonia equivalent to .1% to 5%concentrated ammonia by volume of said oil, heating said mixture to atemperature from 300 F. to incipient cracking temperature of the oil for.01 to 10 seconds at a pressure of 15 to 500 pounds, releasing thepressure, whereby water and ammonia are allowed to escape, cooling andfiltering the resulting oil.

'7. Process of claim 6 wherein the organic acid is a mixture of alkylphenols, and the metal is an alkaline earth metal.

8. Process of claim 6 wherein the organic acid is a mixture of acidsnaturally associated with said oil.

9. Process for producing solutions of basic salts of organic acids inlubricating oils, comprising mixing a lubricating oil containing anorganic acid with an amount of a base of a metal capable of producingoil-soluble salts with said acid, said amount being substantially inexcess of the equivalent of said acid, and a quantity of a strongaqueous ammonia equivalent to .1 %v to 5% concentrated ammonia by volumeof said oil, heating said mixture to a temperature from 300 F. toincipient cracking temperature of the oil for .1 to 10 seconds at apressure of 50 to 500 pounds, releasing the pressure, whereby water andammonia are allowed to escape, cooling and filtering the resulting oil.

ROLAND F. BERGSTROM.

